Cylinders for internal combustion engines, pumps or the like

ABSTRACT

Liner for the bore of the cylinder of an internal combustion engine, pump, bearing, etc., the liner being made from a flat rectangular piece of thin hard springy steel strip, the liner having defined limits of thickness in relation to the bore to be lined as defined by the expression

United States Patent [191 Cross, deceased et al.

. 1 CYLINDERS FOR INTERNAL COMBUSTION ENGINES, PUMPS OR THE LIKE [75] Inventors: Roland C. Cross, deceased, late of Bath, Somerset, England; by Clara Dunbar Cross; Catherine Cross; Philip George Chesterman; Philip Gordon Chesterman, all of Bath, Somerset, EngIariHYREcUtOrs [73] Assignee: (YtEs Ma ritTfacfuring Company (1938) Limited, Bath, Somerset, England [22] Filed: May 26, 1972 [21] Appl. N0.: 257,192

Related U.S. Application Data [63] 'Continuation-in-part of Ser. No. 60,412, Aug. 3,

1970, abandoned.

[52] U.S. Cl 29/156.4 WL, 92/169 [51] Int. Cl 823p 15/00 [58] Field of Search 29/l56.4 WL

[56] References Cited UNITED STATES PATENTS 2,414,931 1/1947 Colwell et al 29/156.4 WL

tiodo Liner fh/ckness inches [4 1 Feb. 19, 1974 Colwell et al.....

2,283,424 5/1942 29/156.4 WL 2,361,434 10/1944 Surtees 29/156.4 WL 2,234,142 3/1941 Janney et al.. 29/156.4 WL 2,170,015 8/1939 Ford 29/l56.4 WL 2,424,878 7/1947 Crook.... 29/156;4 WL 3,069,209 12/1962 Bauer 29/156.4 WL

Primary Examiner-Charles J. Myhre Assistant Examiner-R. H. Lazarus Attorney, Agent, or FirmEmory L. Groff; Emory L. Groff, Jr.

[57] ABSTRACT Liner for the bore of the cylinder-of an internal combustion engine, pump, bearing, etc., the liner being made from a flat rectangular piece of thin hard springy steel strip, the liner having defined limits of thickness in relation to the bore to be lined as defined by the expression Log Thickness (D( 1 1.3 0.9) l0 /Log where D is the internal bore of the cylinder being lined. This strip is sprung into a cylindrical form of outside diameter, when its edges abut together, corresponding to that of the bore.

7 Claims, 8 Drawing Figures Preferred ran qe shown m s cf/orz 10 D/amefer' mc/ves til-v CYLINDERS FOR INTERNAL COMBUSTION ENGINES, PUMPS OR THE LIKE This invention is a continuation-in-part of application Ser. No. 60,412, filed Aug. 3, 1970 now abandoned.

The invention relates to improvements in liners for bores of circular section such as bores of internal combustion engine cylinders, cylinders of pumps, or of compressors, or of bearings. The invention includes the method of lining the bores and the bores when furnished with the liners of the invention.

The invention presents a lined bore in which the liner is inserted in a simple manner whilst providing a true and continuous surface in which the whole of the outer surface of the liner is pressed against the wall of the bore and which requires no finishing steps and can be applied to bores formed in different metals and alloys without distortion of the bore when, e.g., the liner is of a harder metal or alloy than that of the lined bore it provides a more durable surface on the softer metal. The invention makes use of the compressive hoop stress effect as between the liner and the bore metal having regard to their respective Youngs moduli with reference to a particular range of thickness of the liner having regard to the diameter of the bore to be lined whereby a thin, flat sheet of a metal, or alloy, of a selected thickness, suitably dimensioned to the bore to be lined, can be sprung readily into the bore being lined so as to make an interference fit such that there is complete contiguity between the bore wall and the liner without overlap, or the formation of a gap, between the liner edges.

Known split liner sleeves are formed for press fitting into a cylinder so that they will lay firmly against the wall of the cylinder. The press fit is depended upon to provide the force to lay the split liner firmly against the cylinder wall and the liner is placed in a stressed condition but because it has not heretofore been'realized that there is a critical relation between the thickness of the liner and the diameter of the bore being lined, and because insufficient account has been taken of the compressive hoop stress relationship'between the liner and the bore, the press fit has tended to distort the cylinder because of tension forces set up between the walls defining the cylinder bore and the liner. Special tools are required for installation and removal of previous liners and close manufacturing limits are required to maintain an accurate press fit and, even when such limits are closely adhered to, a honing and polishing operation is required after the liner has been press fitted into the cylinder for removing'of remaining defects caused by distortion and the inability of the press fit to effect a complete conformity between the liner and the cylinder. In an attempt to overcome these defects it has been proposed to insert a split liner into a bore, according to the press fitting method, by leaving a gap in the seated liner and this effects a lined cylinder suffereing from the disadvantages attendant upon incomplete contiguity of the liner with the bore that is lined; even in this case it is generally necessary to perform a final honing operation.

In accordance with the instant invention it is of importance that the liner be withindefined limits of thickness related to the bore to be lined; thus, if the liner is too thin it will have a tendency to crumple, or buckle, or at best to make an imperfect fit with the bore being lined, whilst, if it is too thick, the edges of the press fit ted liner will be unlikely to abut, but will leave a gap, or else the assembly of the liner will require an involved series of operations, both of a preparatory nature and for finishing and it has been found, surprisingly, that there is a critical upper and lower limit of liner thickness related to bore diameter beyond which the advantages of the invention are not achieved. These limits are more fully explained by reference to FIG. 1 of the accompanying drawings which is referable to the law:

Log Thickness (D (1l.3/Log 0.9) 10 where D is the internal bore of the cylinder being lined.

It will be seen from FIG. 1 that the range of liner thickness related to diameter is not a linear function and not predictable.

Put another way, the liner thickness may be expressed as where L is the thickness of the liner D is the inside diameter of the bore being lined and X is a factor related to the bore being lined wherein 83 when D 1, 154 when D 2, 2l4 when D 3, 250 when D 4, 300 when D 4.5, 348 when D 8,

343 when D 12, 314 when D= l6, and 267 when D 20.

In a preferred form of the invention the liner material is heat treated steel, i.e., the steel is hardened and tempered and requires no further finishing and the bore material is aluminum or an aluminum alloy. lt will be appreciated that other metals, or alloys, may comprise the liner, or the bore; e.g., the liner may be, for example, brass and the bore material may be cast iron. It will be further appreciated that, for some applications, e.g., bearings, the liner may be the softer metal, e.g., a white metal liner is aluminum.

The liner of the defined degree of thickness is inserted in a bore that is sufficiently strong to withstand the compressive hoop stress imposed by the interference fit of the liner without significant deformation and this ensures that the liner is always tightly butted and in overall contact with the wall of the bore. Because of this contact, and the defined thickness of the liner, heat generated within the lined bore, e.g. when the lined bore is the cylinder of an internal combustion engine, will pass rapidly through the liner to the surrounding bore material, even when the liner is a poorer conductor of heat than the bore material, e.g., when the liner is of heat treated and tempered steel and the bore material is aluminum. Thus, amongst advantages of the invention, are that it permits a bore, e.g., the bore of an engine cylinder, or a bearing, to be readily lined, and at ambient temperature, with a liner presenting an interference fit such that a continuous surface without any gap results, and not requiring any preparatory or finishing operation whereby substantially complete contact between the liner and the lined bore is effected and with improved heat conduction between the liner and the bore material notwithstanding that the liner may be a substantially poorer conductor of heat than the bore material. Furthermore, the liner permits a more durable surface to be applied to a less durable material. I

In the method of the invention a flat piece of liner material, e.g., hard heat treated tempered springy steel, having a thickness within the defined range, and appropriately dimensioned to be an interference fit in the bore being lined when sprung into, and held in, a substantially cylindrical form with its adjacent edges abutting, is sprung-shaped and held in the required configuration and then pressed as an interference fit in the bore, the diameter and circularity of the liner being thereafter controlled solely by the cylinder bore, this control being related to the compressive hoop stresses of the liner and the bore material as governed by their thicknesses and Youngs moduli. The bore to be lined may be provided with a shoulder against which the liner abuts and which is of the same thickness as the liner.

The invention also includes the liner itself consisting of a flat metal, or metal alloy, piece having the defined thickness and an appropriate shape, e.g., a rectangle, and capable of being sprung into the bore to be lined according to the foregoing method as an interference fit without presenting a gap between the edges.

The liner of the invention can be assembled quickly in the bore to be lined whilst both the liner and the bore material are at room temperature contrary to existing methods where liners are frequently required to be kept at very low temperatures whilst being assembled.

Although by no means limited thereto, the invention is particularly useful for lining cylinders of internal combustion engines, steam engines and jet engines. The invention is also useful in presenting improved bearings. In this application it provides a relatively inexpensive, simple bearing, and a method for its production, which previously would not have been thought to have been practicable. Thus the degree of interference fit, having regard to the previously mentioned parameters, i.e., liner thickness of the respective metals, or alloys, and their Youngs moduli, permits the bearing to be made of a material similar to that of the journal, thus reducing problems caused by differential expansion between the journal and the bearing housing and permitting improved heat flow characterictics to be achieved. The invention also allows space and weight considerations to be improved by permitting savings in these to be made in appropriate cases; thus, for example, a hardened and tempered steel liner may be provided as a durable surface on an otherwise desirable but less wear resistant bearing material with which, if desired, a suitable finishing operation can be provided. Thus a hardened and tempered steel liner can be provided with a very fine surface finish which furnishes an excellent bearing surface. Thus there is provided a comparatively inexpensive, light, hardened, ultra-thin, plain and easily fitted bearing surface.

Amongst other advantages of the invention are the very low cost of the liner and the small storage space required; thus many thousands of liners in the flat state will take up only a few cubic feet of space either in a store or on a fitting bench. The liner material, e.g. hard steel, can be chosen to have a very long life when working against a conventional piston and rings, or in a bearing, and fitting at room temperatuere is an easy procedure. It will be appreciated that, apart from cutting the liner blank from strip, which can be a accomplished in a very short time, eg a few seconds, there are no machining operations. The invention when applied to cylinders of internal combustion engines, is equally applicable to air or liquid, e.g., water, cooled cylinders. The invention is advantageously applied to so-called wet liners of internal combustion engines, pumps and the like. Wet liners are well understood in the art to mean separate metal cylinders adapted to be mounted in a cylinder block and surrounded by water or other coolant. In a modification of the invention such a wet liner comprises a composite structure of two metal liners one fixedly fitted within the other, viz the outer liner being a wet liner proper wherein there is a fixed inner liner of smooth surfaced metal, or metal alloy, strip. The outer liner is preferably of a metal, or alloy, having good thermal characteristics for heat transfer, e.g., aluminum, or aluminum alloy, and the inner liner is suitably hardened and tempered steel to provide a long bore life.

In the accompanying drawings, which illustrate example forms of the invention,

FIG. 1, as previously mentioned, is a graph showing the range of liner thickness related to the bore of the material to be lined,

FIG. 2 is a longitudinal section through a lined aircooled cylinder,

FIG. 3 is a longitudinal section through part of a liquid cooled engine cylinder block,

FIG. 4 shows a flat rectangular piece of liner material,

FIG. 5 shows the liner of FIG. 4 shaped to cylindrical form,

FIG. 6 shows a flat piece of liner material in another form,

FIG. 7 shows the liner of FIG. 6 shaped to cylindrical form, and

FIG. 8 shows an example of the invention as applied to a bearing surface.

Referring to the drawings, it will be seen from the graph of FIG. 1 that the curve of the thickness of the liner to bore diameter approaches the vertical as the bore diameter increases, an eventual position will be reached where liner thickness becomes practically constant irrespective of further bore size increase. For small bores, e.g., l to 4.5 inches, the liners are extremely thin and even for large bores the liners are still remarkably thin.

Referring to FIG. 2, there is shown an air-cooled cylinder 11 which has its bore 12 provided with a liner 13 having a thickness within the defined limits and, preferably, forrned of hardened and tempered steel strip. The strip 13 if formed into a cylindrical shape against its inherent springiness and held by a suitable tool with its longitudinal edges (see e.g., FIGS. 4 and 5) 14, or other shaped edges, e.g. oblique (see e.g., FIGS. 6 and 7) 14a, abutting. The diameter of the strip 13, when formed into a cylinder, is such that it makes an interference fit within the bore 12 when it is inserted therein. The cylinder 11 may have a small shoulder or inturned edge 15 to prevent the liner from being pushed out of the bore, or this object may be achieved in other ways as, for example, by means of a circlip set in a groove at the base of the bore. I

In FIG. 3 there is a plurality of cylinders 16 in the form of so-called wet liners mounted in a cylinder block 17 and surrounded by a coolant chamber 18 containing a suitable coolant, e.g., water or other fluid. The wet liners are suitably of a material that possesses good thermal characteristics for heat transfer such as aluminum, or an aluminum alloy, and each wet liner 16 is itself lined with the liner 13.

The thicknessof the liner 13 is exaggerated for clarity.

When fitting the liner strip 13 in the cylindrical bore of its wet liner 16 it is sprung shaped, and held, in a substantially cylindrical form with its adjacent edges 19 abutting and then pressed as an interference fit into the bore of the cylinder 16, its diameter and circularity being controlled by the cylinder bore.

The cylinder 16 may be flanged exteriorly at 20 to seat on a ledge 21 withthe interposition of a suitable packing.

The piston (not shown) reciprocates against the material of the liner 13 and thus runs on a selected liner surface which can be easily dismantled and replaced.

Referring to FIG. 8, 22 is a journal and 23 is a bearing housing. The journal 22 operates in a bearing 24 provided with a liner 25, in accordance with the invention.

The hardness of the liner, when formed of heat treated and tempered steel, is suitably within the range of 400 to 550 (Diamond Hardness Number).

What we claim as our invention is:

1. A method of lining the bore of an internal combustion engine, pump, compressor, bearing, or the like, characterised in that a liner comprising a flat piece of metal or metal alloy, capable of being sprung shaped into a cylindrical form, and of a different'metal or alloy to that of the bore material, is dimensioned such that its edges, when the liner is formed into a cylinder, are abutting and that the cylinder formed therefrom, when press fitted into the bore, is an interference fit therein and has complete contiguity with the bore wall which it lines without overlap, or the formation of a gap, of the liner edges, which comprises shaping the liner material into a cylindrical form, holding said liner in said form whilst inserting it into the bore and pressing said liner as an interference fit into the bore, the compressive hoop stress between the liner and bore material being such that the diameter and circularity is thereafter controlled solely by the cylinder bore without deformation of the bore and characterised further in that the thickness of the liner in relation to the bore is within the range of 0.008 to 0.019 and calculated in accordance with the equation Log T =(D (1l.3/Log 0.9) 10 Where I is the liner thickness and D is the diameter of the bore, said bore, when lined, requiring no further finishing steps.

2. A method of lining the bore of an internal combustion engine, pump, compressor, bearing, or the like, characterised in that a liner comprising a flat piece of metal, or metal alloy, capable of being sprung shaped into a cylindrical form, and of a different metal or alloy to that of the bore material, is dimensioned such that its edges, when the liner is formed into a cylinder, are abutting and that the cylinder formed therefrom, when press fitted into the bore, is an interference fit therein and has complete contiguity with the bore wall which it lines without overlap, or formation of a gap, of the liner edges, which comprises shaping the liner material into a cylindrical form, holding said liner in said form whilst inserting it into the bore and press fitting said liner as an interference fit into the bore the compressive hoop stress between the liner and the bore material being such that the diameter and circularity of the liner is thereafter controlled solely by the cylinder bore without deformation of the bore and characterised further in that the thickness of the liner in relation to the bore where L is the thickness of the liner,

D is the inside diameter of the bore to be lined and X is within the range of:

62 to 125 when D= 1, M7 to 222 when D 2, 166 to 300 when D 3, 210 to 364 when D= 4 or when D exceeds 4, said bore, when lined, requiring no further finishing steps.

3. A method of lining a bore as claimed in claim 2' wherein X is within the range of:

71 to when D= l,- 133 to 182 when D= 2, 200 to 250 when D 3, 222 to 286 when D 4 or is greater than 4. 4. A method as claimed in claim 3 wherein X is within the range of:

83 when D= l, 154 when D 2, 214 when D 3, 250 when D 4, 300 when D 4.5, 348 when D 8.

material is aluminum or aluminum alloy. 

1. A method of lining the bore of an internal combustion engine, pump, compressor, bearing, or the like, characterised in that a liner comprising a flat piece of metal or metal alloy, capable of being sprung shaped into a cylindrical form, and of a different metal or alloy to that of the bore material, is dimensioned such that its edges, when the liner is formed into a cylinder, are abutting and that the cylinder formed therefrom, when press fitted into the bore, is an interference fit therein and has complete contiguity with the bore wall which it lines without overlap, or the formation of a gap, of the liner edges, which comprises shaping the liner material into a cylindrical form, holding said liner in said form whilst inserting it into the bore and pressing said liner as an interference fit into the bore, the compressive hoop stress between the liner and bore material being such that the diameter and circularity is thereafter controlled solely by the cylinder bore without deformation of the bore and characterised further in that the thickness of the liner in relation to the bore is within the range of 0.008 to 0.019 and calculated in accordance with the equation LogeT (D (11.3/Loge3) - 0.9) 10 2 Where T is the liner thickness and D is the diameter of the bore, said bore, when lined, requiring no further finishing steps.
 2. A method of lining the bore of an internal combustion engine, pump, compressor, bearing, or the like, characterised in that a liner comprising a flat piece of metal, or metal alloy, capable of being sprung shaped into a cylindrical form, and of a different metal or alloy to that of the bore material, is dimensioned such that its edges, when the liner is formed into a cylinder, are abutting and that the cylinder formed therefrom, when press fitted into the bore, is an interference fit therein and has complete contiguity with the bore wall which it lines without overlap, or formation of a gap, of the liner edges, which comprises shaping the liner material into a cylindrical form, holding said liner in said form whilst inserting it into the bore and press fitting said liner as an interference fit into the bore, the compressive hoop stress between the liner and the bore material being such that the diameter and circularity of the liner is thereafter controlled solely by the cylinder bore without deformation of the bore and characterised further in that the thickness of the liner in relation to the bore is L D/X where L is the thickness of the liner, D is the inside diameter of the bore to be lined and X is within the range of: 62 to 125 when D 1, 117 to 222 when D 2, 166 to 300 when D 3, 210 to 364 when D 4 or when D exceeds 4, said bore, when lined, requiring no further finishing steps.
 3. A method of lining a bore as claimed in claim 2 wherein X is within the range of: 71 to 100 when D 1, 133 to 182 when D 2, 200 to 250 when D 3, 222 to 286 when D 4 or is greater than
 4. 4. A method as claimed in claim 3 wherein X is within the range of: 83 when D 1, 154 when D 2, 214 when D 3, 250 when D 4, 300 when D 4.5, 348 when D
 8. 5. A method as claimed in claim 1 in which the liner material is of a harder nature than that of the bore material.
 6. A method as claimed in claim 1 wherein the liner is of hardened and tempered steel.
 7. A method as claimed in claim 6 in which the bore material is aluminum or aluminum alloy. 